The semiconductor industry is continuously moving toward the fabrication of smaller and more complex microelectronic components with higher performance. Memory cells are an important part of many microelectronic components, and smaller and more reliable memory cells are desirable. One type of memory cell is a non-volatile and re-writable memory cell. Non-volatile memory cells retain stored information even when the memory cell is de-powered, and stored information can be changed when the memory cell is re-writable. Some non-volatile, re-writable memory cells store information using a phase change material, where the phase change material has two stable states with different properties. For example, the two stable states may be different stable atomic lattice states. The varying property of the non-volatile, re-writable memory cell can be measured to determine its' state. For example, germanium antimony tellurium (GeSbTe, or more commonly GST) has a stable crystalline state and a stable amorphous state, with the respective states having different electrical resistivities. The state of the GST can be changed with controlled temperature variations, and the resistance or resistivity of the GST memory cell can be measured to determine if the GST material is in the crystalline or amorphous state. One state is equated with a “0,” and the other state is equated with a “1,” as is typical for memory cells.
Many GST memory cells are horizontal, where the GST material is positioned between a first and second electrode, and the GST material and first and second electrodes are all on the same level. However, the horizontal structure occupies a large footprint that is not conducive to the fabrication of smaller integrated circuits. Some vertical GST memory cells include an upper and lower electrode with the GST material positioned therebetween, but the GST material has a large cross-sectional area between the upper and lower electrodes. The temperature changes used to switch the GST material between the different states are produced by inducing a current through the GST material to generate heat. The large cross-sectional area requires a high current density to produce the required temperatures for phase change between the two states. This high current density drains power and is undesirable in integrated circuits.
Accordingly, it is desirable to provide integrated circuits and methods of manufacturing integrated circuits using phase change memory cells that occupy a small footprint. In addition, it is desirable to provide integrated circuits and methods of forming them with a phase change memory cell that requires a small current density to control a change in the phase change material. Furthermore, other desirable features and characteristics of the present embodiment will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.